With the ever present desire to produce new designs for the fashion and home furnishings industries the nature of the slide or zip fastener on a particular garment or article can have a significant effect on the overall look of the finished article.
In addition, however, whilst having an attractive appearance, a slide fastener has a functional role and is often key to the garment or home furnishing.
A problem associated with slide fasteners is the inherent nature of the coupling or fastening elements or teeth that form the closure mechanism for the slide fastener to receive foreign materials. The presence of the foreign materials, if left unchecked may damage the closure mechanism by preventing movement of a slider along the length of the slide fastener. In addition, removal of the foreign body may result in damage to the coupling elements or teeth such that the fastener may no longer close.
Furthermore, in many slide fasteners the coupling or fastening elements may also provide rough edges, particularly when metal teeth are used as the coupling elements such that if a piece of for example a garment does become entangled in the slide fastener, the mode of operation of the slide fastener may damage the garment as the slide fastener is closed and then reopened to free the garment from the slide fastener.
There is therefore a need to provide a slide fastener with a closure mechanism which does not possess any rough edges on the coupling elements, which is attractive in appearance and which still possesses an efficient closure compared with existing slide fasteners.
In conventional slide fasteners there is usually provided a pair of fastener tapes upon which are mounted rows of individual coupling elements which cooperate and interdigitate when the fastener tapes pass through a slider mounted on one of the fastener tapes and in so doing either close or open the slide fastener accordingly.
However, the interdigitation of the coupling elements has a limiting effect on the visible appearance of the slide fastener. That is, due to the required interconnection of the coupling elements needed to ensure a sufficient closing of the slide fastener, the design of the external appearance of the slide fastener has been strictly limited.
In addition, the interconnection of the coupling elements visible to the user on the front and rear of the fastener has limited the flexibility of the slide fastener in the closed position and also the separation between the individual fastener elements on opposing fastener tapes.
For example, in U.S. Pat. No. 7,320,158 B2 (YKK Corporation) there is described a fastener with two fastener tapes in which the individual magnetic elements mounted on the opposed inner longitudinal edges of two fastener tapes at predetermined intervals are each adapted to fit between and be attracted to two mating magnetic elements mounted on the opposite fastener tape. Whilst this invention overcomes the problem of unsightly slide fastener closures and provides an attractive and smooth fastener, the strength of the fastener is limited by the strength and hence size of the magnets employed on the fastener tapes.
In WO 2005/101974 (Artzip Ltd) there is disclosed a zipper comprising two opposed rows of discrete interlocking elements wherein each of the interlocking elements carries a design or a fragment thereof for example, a trademark, logo or emblem. Whilst WO 2005/101974 details fastening elements wherein the front face of the fastening elements comprise a different design to the rear face of the fastening elements, the interdigitation between the individual fastening elements on opposing sides of the fastener tapes comprising the zipper is reduced thereby resulting in a weakened slide fastener or zipper.
In addition, the elaborate nature of the fastening elements on the front face of the slide fastener means that excessive flexing of the slide fastener when in the closed position may impair the closure of the fastener elements and therefore overall lead to a zipper with reduced flexibility.
In U.S. Pat. No. 7,353,570 (YKK Corporation) there is described a fastener chain in which fastener elements each formed into a single unit of synthetic resin are attached at a constant interval along opposing side edges of a pair of fastener tapes. Each fastener element comprises a front surface portion and a rear surface portion which are different with respect to one another. Both faces of the fastener elements are intricately fabricated thereby producing a fastener chain with an improved tactile feel and appearance but with a complicated design thereby making the fastener expensive and difficult to produce.
Finally, in U.S. Pat. No. 7,337,509 (YKK Corporation) there is described a slide fastener wherein the fastener elements comprise a main body element constituted of a base portion attached to a fastener tape, a neck portion and an engaging head portion continuous from the neck portion. Also present is a stiffening means on the main body element allowing the surface stringers to bend when the elements are separated and inhibiting the fastener chain from bending when the elements are engaged in a stiffening condition.